Encapsulation of oleophilic substances and compositions produced thereby

ABSTRACT

Multiple micro-encapsulations of a high concentration oleophilic substance using heat to set the primary particle renders the composition suitable for the production of free-flowing powders or beadlets. Microencapsulation involves forming an emulsion out of the oleophilic substance and a polymer, and then use heat setting and/or cross-linking the polymer encapsulates the oleophilic composition. This process is then repeated with a second polymer or third polymer, and with or without cross-linked via the same or different mechanism to further protect the oleophilic substance.

This is a divisional of U.S. application Ser. No. 09/008,251, filed Jan. 16, 1998, now U.S. Pat. No. 6,001,554 which is a continuation of U.S. application Ser. No. 08/439,787, filed May 24, 1995, now U.S. Pat. No. 5,938,990, which is a continuation-in-part of U.S. application Ser. No. 08/269,720, filed Jul. 1, 1994, abandoned.

FIELD OF THE INVENTION

The invention relates to encapsulation of oleophilic substances (as used herein the term "oleophilic" is to embrace fat- and oil-soluble substances as well as fats and oils), and to compositions produced by this process. In particular, the invention relates to the preparation of high potency, dry and free-flowing vitamin powders/beadlets using multiple microspheric and/or microencapsulation techniques.

BACKGROUND OF THE INVENTION

Oleophilic substances, and in particular fat-soluble vitamins such as A, D, E and K, have had limited incorporation into dry materials because of their oil-like nature. Accordingly, oleophilic substances have tended to be macroencapsulated and delivered as units of coated oil. Unfortunately, however, such delivery drastically restricts the applications for which these oleophilic substances are suitable. For example, current commercial techniques can only produce concentrations of vitamin E which range up to 50% by weight.

The present invention overcomes the limitations inherent in the prior art encapsulation techniques and allows for production of high potency vitamins in a free flowing powder form. Such a form allows for delivery into multiple vitamin tablets or foods, such as cereal, and provides the advantages of reducing tablet size or the bulk required for subsequent delivery. Of particular interest is high potency Vitamin E in which Vitamin E forms greater than about 50% by weight of a dry powder or beadlet.

The prior art, as represented by Lim, et al., U.S. Pat. No. 4,389,419, issued Jun. 21, 1983, the contents of which are herein incorporated by reference, describes the formation of an emulsion consisting of a continuous phase aqueous solution of an alkali metal alginate, and optionally, a water-soluble alcohol-insoluble filler such as a polysaccharide, and a dispersed phase of an oleophilic substance. The emulsion thus produced is then formed into droplets which are emersed into an alcoholic solution of multi-valent cations, to produce a water-insoluble shape-retaining alginate matrix filled with precipitated polysaccharide and enclosing plural oil droplets.

The Lim, et al. approach differs markedly from that of the subject invention in which an oleophilic substance is incorporated into a primary polymer containing solution, and then solidified under mixing conditions to encapsulate the fat-soluble substance and form an encapsulated fat-soluble composition. Through the use of mixing conditions in forming the primary particle, far greater concentrations of oleophilic substances relative to those achieved by Lim, et al. can be realized. As stated by Lim, et al., the amount of oil may range from between 1% up to nearly 30%. However, at the higher end of this range, the stability of the Lim, et al. oil-in-water emulsion is decreased and the quality of the Lim, et al. microcapsule is reduced. Additionally, the Lim, et al. droplets need to be removed from the alcoholic solution and washed, or otherwise treated, to remove any residual alcohol, thus requiring extra production steps.

Another markedly different approach employed for encapsulating vitamin or mineral nutrients, such as thiamine, is described by Hall, et al., U.S. Pat. No. 4,182,778, issued Jan. 8, 1980, the contents of which are herein incorporated by reference. Hall, et al. describes encapsulation by fluidizing the nutrient in a gaseous stream and contacting the nutrient with finely atomized droplets of a coating solution. Nowhere, however, is the application of the Hall, et al. suggested for use with oleophilic substances.

As described below, the concentration of the oleophilic substance in the subject invention typically ranges from about 30% to about 90% based on the dry weight percentage of the final encapsulated oleophilic composition. These percentages are far superior to those described by Lim, et al., and form a major breakthrough over the current state of the art which only allows percentages of vitamin E to reach about 50%. Thus, the subject invention fulfills a long-felt need in the art for a high potency encapsulated oleophilic composition.

SUMMARY OF THE INVENTION

The invention provides a method for producing a composition which encapsulates an oleophilic substance. This method comprises incorporating an oleophilic substance into a primary polymer-containing solution, and solidifying the primary polymer under mixing conditions to encapsulate the oleophilic substance within the polymer and form the composition.

Typically, the primary polymer is a cellulose, such as methylcellulose and hydroxypropyl methylcellulose, and the oleophilic substance is a fat-soluble vitamin, such as vitamin A, D, E, and K. Preferably, the concentration of the oleophilic substance ranges from about 30% to about 90% based on a dry weight percentage of the final encapsulated composition.

Also provided is a preferred method for producing a composition encapsulating an oleophilic substance. This method involves incorporating an oleophilic substance into a primary polymer-containing solution, solidifying the primary polymer under mixing conditions to encapsulate the oleophilic substance within the polymer and form a primary particle, and adding a secondary polymer under mixing conditions to further encapsulate at least one primary particle within the secondary polymer and form the composition (secondary particle). Of course, multiple primary particles may be encapsulated to form a single secondary particle, and the mixing conditions may vary between the first and second encapsulation.

As with the first method, the primary polymer is usually a cellulose, such as methylcellulose and hydroxypropyl methylcellulose. The secondary polymer is generally a cellulose, cellulose derivative, maltodextrin, such as a maltodextrin having a dextrose equivalent value of about 18, alginate, calcium lactate, acacia, gelatin, such as fish gelatin, or modified starch, such as hydroxypropyl starch or pregelatinized corn starch.

Preferred celluloses include methylcellulose and hydroxypropyl methylcellulose, and preferred cellulose derivatives include hydropropylmethyl cellulose phthalate.

In a preferred embodiment, the secondary polymer is used to encapsulate the primary particle. Such encapsulation may be achieved by changing the pH, by adding a cross-linking agent, by heating, by spray drying, or by other suitable means. Example of cross-linking agents include. sugar, acacia, cations, or gelatin.

Further provided by the subject invention are compositions produced by the above methods.

One composition encapsulating an oleophilic substance comprises an oleophilic substance, a first polymer which encapsulates the oleophilic substance to form a primary particle, and a second polymer which encapsulates at least one primary particle. The choices of primary and secondary polymers are as described above.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 An illustration of a powder/beadlet showing the multi-microencapsulation structure formed in one embodiment of the present invention.

FIG. 2 A scanning electron micrograph (SEM) of a vitamin E powder (X100).

FIG. 3 SEM of a vitamin E powder (X200).

FIG. 4 SEM of sectioned vitamin E powder (X100).

FIG. 5 SEM of sectioned vitamin E powder (X500).

FIG. 6 SEM of vitamin A-palmitate (X50).

FIG. 7 SEM of vitamin A-palmitate (X200).

FIG. 8 SEM of sectioned vitamin A-palmitate (X300).

FIG. 9 SEM of sectioned vitamin A-palmitate (X500).

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in terms of its preferred embodiments. These embodiments set forth to aid in the understanding of the invention, but are not to be construed as limiting. Throughout the specification, percentages are by weight percent and temperatures are ° C., unless noted otherwise.

One inventive aspect of the subject invention is the production of high potency (generally from about 30 to about 90 weight percent) fat-soluble vitamins (such as A, D, E and K) in the form of dry powders and/or beadlets.

These vitamin powders and/or beadlets can be prepared by (1) emulsifying vitamin oils (such as vitamins A, D, E or K) in a polymeric solution (such as a cellulose or cellulose derivative), (2) dispersing vitamins (present as crystals) in a polymeric solution to form a suspension, or (3) dissolving and/or diluting fat-soluble vitamins in oil, then emulsifying the vitamin-oil solution in a polymeric solution to form an emulsion. Typically, the polymeric solution will be an aqueous solution.

Then, after the emulsifying, dispersing, dissolving and/or diluting, the emulsion or suspension is heated to a polymeric setting temperature (typically greater than 50° C.) under mixing conditions to produce primary particles (e.g., microcapsules and/or microspheres). Alternatively, the polymer can be cross-linked. In each of these three above scenarios, the oleophilic substance is present as a liquid during at least a portion of the processing time, and typically throughout processing.

For ease in describing the subject invention, emulsifying, dispersing, dissolving and diluting will collectively be referred to as "incorporating."

The term "mixing conditions" refers to a state of imparted movement, such as that associated with stirring, shaking, agitating, jumbling, etc., which is vigorous enough to cause the emulsion or suspension to solidify as particles. Mixing conditions are readily determined by a skilled artisan who has read the present specification using known techniques, for example, by using an anchor stirrer, homogenizers, colloidal mills, microfluidizers, sonicators, or impellers (mechanical stirring). Particle size can be varied by changing the amount of imparted movement. For example, slow stirring will generally produce a larger particle size than will fast stirring. The examples which follow provide ample guidance for one skilled in the art to determine appropriate mixing conditions without undue experimentation.

Microcapsules are formed by a single encapsulation, whereas microspheres are conglomerates of multi-oil droplets embedded in a spherical or sphere-like matrix. The term "primary particle" as used herein refers to micro- and/or macro-particles, produced by either heat inducing (setting), coacervating or cross-linking a polymer-containing emulsification. For convenience, cross-linking, coacervating and thermal setting will collectively be referred to as "solidifying."

Theoretically, preparation of oleophilic substances in a primary polymer-containing solution to form an emulsion or suspension can be performed at any temperature. However, the practical temperature range for this step depends on the nature of polymer chosen. For example, in preparing an HPMC emulsion, the preferred temperature should be between room temperature and no higher than 60° C. The skilled artisan is readily able to determine an acceptable temperature range based on the components chosen.

The solidification step for making the primary particles is physically determined by the mechanism and process temperature. For instance, if solidification is caused by cross-linking, such as with an alginate emulsion cross-linking with calcium ions, temperature may not be critical. That is, processing can be effected at any temperature. However, when HPMC is chosen as the main polymer for the primary particles, and heating is the main mechanism utilized to make primary particles, temperature becomes important and must be maintained above 60° C. throughout the whole process. Again, these parameters are determinable to the skilled artisan, having read the present disclosure.

Primary particles may then be further encapsulated with a secondary, or secondary and tertiary (depending on whether the primary particles are microcapsules or microspheres) polymeric layer(s) by the addition of a second polymer to the suspension followed by solidifying the second polymer (such as cross-linking by adding a cation, or by changing the pH) to form a secondary particle. The term "secondary particle" as used herein refers to a primary particle which has been further encapsulated or coated. The term "encapsulated" also includes the term "coated". Of course, multiple primary particles (at least 2) may be encapsulated or coated to form a single secondary particle.

Although the current method of production first solidifies the primary polymers by heating to form the primary particles and then simply coats or chemically cross-links the secondary polymers to form the secondary particles, alternate methods of solidifying may be utilized. Additionally, further encapsulations of the secondary particles, such as coating or polymerization around the secondary particles, may be effected.

Secondary and tertiary polymers are typically celluloses (e.g., methylcellulose or hydroxypropyl methylcellulose), cellulose derivatives (e.g., hydroxypropyl methylcellulose phthalate), alginates (e.g., sodium alginate or propylene glycol alginate), modified starches (e.g., pregelatinized corn starch or hydroxypropyl starch), calcium lactate, gelatins (e.g., fish gelatin), maltodextrins (e.g., dextrin having about 18 dextrose equivalent value, D.E.=18), or acacias. The final mixture may be sprayed dried or processed by any suitable drying techniques to powder or beadlet form which has high potency, is dry and free-flowing, and is suitable for tableting or encapsulation within soft or hard gelatin capsules. Such powders may also be used in food, animal feed, or other pharmaceutical applications, such as premix, suspension and emulsion.

The addition of secondary and/or tertiary polymer onto the primary particles is based on the same principle as described above. The proper temperatures, pH ranges, and ionic strengths for adding the second and/or third polymer varies depending on the types of materials and mechanisms used.

Experimental Detail

EXAMPLE 1 High Potency Vitamin E Acetate Using Methocel E 15LV as the Primary Polymer, Sodium Alginate As the Second Polymer, and HPMC 6 cps as the Tertiary Polymer

    ______________________________________                                                        FORMULA IA  FORMULA IB                                            INGREDIENTS % %                                                              ______________________________________                                         Vitamin E acetate                                                                             75 + 2% overage.sup.1                                                                      75 + 2% overage.sup.1                                 Methocel E 15LV.sup.2 13.0 20.0                                                Kelton LV/CaCloride.sup.3  2.0 2.0                                             Ratio 1:0.5                                                                    HPMC, 6 cps.sup.4 10.0 3.0                                                   ______________________________________                                          .sup.1 Overage is standard in the industry to ensure that the final            product contains at least the given percentage. Therefore, a 2% overage        was added.                                                                     .sup.2 Methocel E15LV refers to a special grade of hydroxypropyl               methylcellulose manufactured by Dow Chemical Co.                               .sup.3 Keltone LV refers to the trade name for sodium alginate from the        Kelco, Division of Merck & Co. Inc.                                            .sup.4 HPMC, 6 cps refers to hydroxypropyl methylcellulose 2910, such as       that manufactured by SHIETSU Co. ("PHARMACOAT 606"). "Cps" is the              viscosity unit "centiopoise," is commonly referred to in the industry, an      is referenced throughout the specification.                              

Procedure

1. Sodium alginate solution (5% w/w) was prepared in a 2 liter (1) beaker as follows:

    ______________________________________                                         Preparation of 5% sodium alginate                                                Time    Temperature                                                                              Stirrer speed                                                (min.) (° C.) (rpm) Amount Comments                                   ______________________________________                                         0     20                  1.27 l                                                                               Add water to beaker and                              stir                                                                       5 20 1200 66.7 g Add sodium alginate                                            25 2000  Heat suspension to                                                       70° C., and maintain                                                    temperature and agitation                                                      until the solution is used                                               ______________________________________                                    

2. Calcium chloride solution (5% by weight) was prepared in a 1 l beaker as follows:

    ______________________________________                                         Preparation of 5% calcium chloride                                               Time    Temperature                                                            (min.) (° C.) Stirrer Amount Comments                                 ______________________________________                                         0               --      0.633 l                                                                              Add water to beaker                                1  on 33.3 g Add calcium chloride                                              2 22 on  Stir and maintain                                                         temperature at 70° C. until                                             used                                                                     ______________________________________                                    

3. HPMC, 6 cps solution (12% by weight) was prepared in a 5 l beaker as follows:

    ______________________________________                                         12% HPMC, 6 cps                                                                  Time    Temp.   Stirrer speed                                                  (min.) (° C.) (rpm) Amount Comments                                   ______________________________________                                          0    21                2.45 l                                                                               Add water to beaker and                                heat to 90° C.                                                      32 90 1000 0.5 kg Slowly add HPMC 6 cps                                            powder with agitation                                                      52 86  200  Addition completed                                                     Remove heating source                                                      82 91 1000 1.22 l Rapidly add cold water                                           (rapid cooling)                                                                Cool to room temperature                                                       while maintaining gentle                                                       agitation until use                                                      ______________________________________                                    

4. Methocel E15LV solution (10%) was prepared using the same procedure as described in step 3. Essentially, Methocel E15LV was dispersed in 90° C. water, stirred and then uniformly dissolved in the water while the temperature was cooled.

5. Vitamin E acetate (an oil) was added to the Methocel solution according to the above formula, and homogenized using a colloidal mill until an emulsion having the smallest possible oil droplet size was reached. Although average droplet size tends to vary, droplets less than about 3 μm in diameter are satisfactory for most uses. Typically, average droplets range between about 0.5 and 1 μm in diameter, even though smaller diameters are generally preferred. (During emulsification, a cooling system was applied to maintain the temperature at approximately 25° C.).

6. The emulsion was then heated to about 80-90° C. while mixing slowly (at about 200 r.p.m.) with an anchor stirrer.

7. Warm (70° C.) 5% alginate solution was then added and the mixture was mixed slowly (at about 200 revolutions per minute (r.p.m.) with an anchor stirrer) while maintaining temperature above 70° C.

8. The mixture was maintained at about 70° C. for approximately 15 minutes, and then cross-linked by adding 5% calcium chloride solution.

9. HPMC 6 cps 12% solution at room temperature (RT) was added in small aliquots while maintaining the temperature above 70° C.

10. Water was then added to adjust viscosity to less than about 2,000 cps (in this particular instance 1,000 cps) for spray drying.

11. The solution was then spray dried under conventional conditions.

A specific vitamin E emulsion was prepared in a FRYMA processing unit (homogenizer, different types of mixers, and cooling and heating system) manufactured by Fryma, Inc., as follows:

    ______________________________________                                         Preparation of the vitamin E emulsion and suspension                                                   Col-                                                     Time Temp. Anchor loidal Dis-                                                  (min.) (° C.) stirrer mill solver Amount Comments                     ______________________________________                                          0    26      on      --   --     6.5 kg                                                                              Add 10%                                         Methocel solution                                                              to vessel                                                                10 26 -- -- -- 3.83 kg Add vitamin E                                                 acetate to above                                                               solution                                                                 18 27 on on on  Start                                                                emulsification                                                           23  on on on  Sample 1: particle                                                     size of oil                                                                    droplets 790 nm                                                          28  on on on  Sample 2: particle                                                     size of oil                                                                    droplets 713 nm                                                          33  on on on  Sample 3: particle                                                     size of oil                                                                    droplets 768 nm                                                          33  on -- --  Emulsification                                                         ended; begin                                                                   heating to 85° C.                                                       and maintain a                                                                 proper agitation                                                               throughout the                                                                 whole process                                                            110  35 on -- --  Add sodium                                                         alginate solution                                                              (75° C.)                                                          115  83 on -- --  Mix 15 minutes                                               130  82 on -- --  Add calcium                                                        chloride solution                                                              (75° C.)                                                          132  85 on -- --  Add HPMC 6 cps                                                     solution (75° C.)                                                 145  85 on -- --  Begin cooling                                                165  82 on -- --  Mix at room                                                        temperature                                                              195  22 on -- --  Heat up to 75° C.                                     245  19 on -- --  Measure                                                            viscosity:                                                                     4300 cps                                                                 255  73 on -- -- 21 Add water to                                                     adjust viscosity                                                               to 1000 cps                                                            ______________________________________                                    

Spray dry the above vitamin E suspension using a NIRO spray dryer; operation with air. This spray dryer is manufactured by Niro, Inc.

EXAMPLE 2A High Potency Vitamin E Acetate Using Methocel E15LV as the Primary Polymer and HPMCP HP-55S as the Secondary Polymer

    ______________________________________                                                       85%    80%    75%   70%  65%  50%                                  INGREDIENTS E E E E E E                                                      ______________________________________                                         Vitamin E acetate                                                                            85     80     75    70   65   50                                   Methocel E15LV 10.0 13.4 16.7 20 23.4 33.4                                     HPMCP grade HP-55S* 5.0 6.6 8.3 10 11.6 16.4                                 ______________________________________                                          Note:                                                                          A 2% overage for Vitamin E acetate was used for each formula.                  *To dissolve HPMCP, 4.5 ml of 0.5N NaOH per gram of HPMCP was utilized.        Once HPMCP completely dissolved in the alkaline solution, water was added      to adjust the solution to 15% solid content.                             

Procedure

1. HPMCP HP-55S solution (15% by weight) was prepared in a 100 l vessel as follows:

    ______________________________________                                         Preparation of 15% HPMCP HP 55s Solution                                         Time                                                                           (min.) Temp. (° C.) Stirrer Amount Comments                           ______________________________________                                          0    16        on      14.94 l                                                                              Add water into the vessel                           5 15 on 300 g Add sodium hydroxide                                                slowly                                                                     10 16 on  Addition ended                                                       15  on 3.32 kg Add HPMCP HP-55S                                                    powder to above solution                                                       with agitation                                                             35 14 on  Addition ended, start                                                    heating                                                                    215  65 on 3.57 l Add 70° C. hot water                                      Stir the solution until use                                              ______________________________________                                    

2. Methocel E15LV solution (10%) was prepared as in Example 1.

3. Vitamin E acetate was added to the Methocel solution according to the above formulas and homogenized to produce an emulsion as in Example 1.

4. The resulting emulsion was heated to 80-90° C. with slow (200 r.p.m.) mixing with an anchor stirrer.

5. An amount of warm (70° C.) 15% HPMCP solution was added. The amount added corresponded to the amount recited in percentage table shown above.

6. The temperature of above mixture was kept at about 80° C. and cross-linked by adding HCl (0.1 N), with mixing, to shift the pH to approximately 5 (about 4.9-5.2).

7. The cross-linked solution was allowed to equilibrate for approximately 45 minutes.

8. The resulting cross-linked solution was then spray dried at the conditions shown below to form a powder.

    __________________________________________________________________________     Spray drying of the vitamin E suspension                                         The suspension was pumped from the FRYMA processing unit to the spray        tower by a                                                                       gear pump and then atomized by a rotary atomizer from Niro, Inc.                                  Set                                                                                          Set Inlet Inlet Set outlet Outlet                                            Pressure Pressure In at air                     Time Temp. Temp. Temp. Temp. Tower Tower flow in                               (min.) (° C.) (° C.) (° C.) (° C.). in mbar                                       in mbar m3/n Comments                         __________________________________________________________________________      0  180     100      -5          Start up lower                                  50 180 181 100 101 -5 -3 1500 Start spray                                              drying                                                                 60 180 181 100 100 -5 -3 1500                                                  62        Spray drying                                                                 ended                                                                __________________________________________________________________________

The "Set Pressure Tower" is the setting for the equilibrium condition in the dryer. In contrast, the "Pressure Tower" is the actual presure reached in the dryer during spray drying.

EXAMPLE 2B High Potency Vitamin E Acetate Using Methocel E15LV as the Primary Polymer and Fish Gelatin, Maltodextrin, Pregelatinized Corn Starch, Calcium Lactate, or Hydroxypropyl Starch as the Secondary Polymer

Following the procedure in Example 2A (with HPMCP being replaced by another secondary polymer), several different secondary polymers were evaluated as follows:

    ______________________________________                                                                                 Hydroxy-                                  Fish  Preglatinized Calcium propyl                                             Gelatin Maltrin Corn Starch Lactate Starch                                    INGREDIENTS 75% E 75% E 75% E 75% E 75% E                                    ______________________________________                                         Vitamin E 75      75      75      75    75                                       Acetate                                                                        Methocel E15LV 16.7 16.7 16.7 16.7 16.7                                        Fish Gelatin 8.3 --  -- -- --                                                  Maltrin M180.sup.1 -- 8.3 -- -- --                                             Pregelatinized -- -- 8.3 -- --                                                 Corn Starch                                                                    Calcium Lactate -- -- -- 8.3 --                                                Hydroxypropyl -- -- -- -- 8.3                                                  Starch                                                                       ______________________________________                                          .sup.1 Brand of maltodextrin (D.E. = 18).                                

Analysis of the five secondary polymers provided the following results using standard test procedures:

    ______________________________________                                                   Fish  Maltrin PreGel         HP                                        Gelatin M180 Starch CaLactate Starch                                         ______________________________________                                         Flow   sec./100 g                                                                              27      23    28    17     39                                    (Agway)                                                                        Density g/ml  0.34  0.39  0.33  0.50  0.34                                     Tapped g/ml  0.39  0.44  0.38  0.56  0.39                                      Density                                                                        Moisture % 1.3 1.0 2.8 0.8 1.0                                                 Color W1E313 37.87 54.26 51.43 53.65 50.10                                      Y1E313 13.22  9.18  9.96  9.12  9.94                                          Static observed High Medium Low Medium Very                                          High                                                                     Free Oil.sup.5 % 2.4 1.6 2.3 2.9 2.2                                         ______________________________________                                          .sup.5 Free Oil refers to the percentage of unencapsulated vitamin E, and      was determined as follows:                                               

Procedure for Measuring Free Oil on Powder Surface

Procedure for Preparing Sample Solution

1. Transfer 0.250 g of powder (vitamin E 75%) to a suitable container.

2. Add 43.0 g of light mineral oil (Fisher).

3. Shake on a mechanical shaker at medium speed for 15 minutes.

4. Pass through a 0.45 μm filter.

5. Measure the UV absorption of the filtrate at 285 nm to determine the abs(sample). Compare against known vitamin E acetate standard (Std).

Procedure for Preparing Standard Solution

1. Weigh 150 mg vitamin E oil standard in a suitable container.

2. Add 86.0 g light mineral oil to above container.

3. Mix using a mechical shaker at medium speed for 15 minutes.

4. Remove 2.5 g of above solution and transfer to an appropriate container.

5. Add 43.0 g of light mineral oil to the container and shake for an additional 15 minutes.

6. Measure the u.v. absorbtion of above solution at 285 nm to determine abs(Std.).

Calculations: ##EQU1## % Free Oil in powder (% unencapsulated vitamin E)=X/(0.25×0.75)×100

Procedure for Evaluating Powder Suitability for Tabletting

The powders of the subject invention are useful in producing antioxidant tablets. To demonstrate their suitability and tabletting performance in antioxidant tablets, tablets were prepared at 4,000 lb pressure using a rotary press.

    ______________________________________                                         TABLETTING PERFORMANCE OF VITAMIN E 75% POWDERS                                  IN ANTIOXIDANT TABLETS AT 4000 LB PRESSURE                                     USING ROTARY PRESS                                                           ______________________________________                                         Election Force                                                                           lbs     47      40    41   38    43                                    Hardness Avg scu 15 17.1 16.9 12.3 12.9                                        Range  11.7-  15.6- 15.8- 11.1- 11.8-                                            16.9 18.3 18 13.6 13.6                                                       Disintegration minutes 15 15 20 14 14                                          Friability % 0.03 0.07 0.09 0.08 0.09                                        ______________________________________                                    

The above results were obtained using the following antioxidant formula:

    ______________________________________                                         ANTIOXIDANT FORMULA                                                              USING VITAMIN E75, BETATAB R AND C-90 GLOBAL                                                  claim   %                kg/90 kg                               Ingredients tablet overage mg/tab % Batch                                    ______________________________________                                         BetaTab R 7.5%                                                                               6 mg   35      108   11.55                                                                               10.395                                   (Beta Carotene 7.5%                                                            Beadlets)                                                                      Vitamin C-90 Global 250 mg 5 292 31.23 28.107                                  Vitamin E 75% 200 IU 5 280 29.95 26.955                                        Microcel C    97 10.37  9.333                                                  (Calcium Silicate)                                                             Avicel PH 102    56  5.99  5.373                                               (Microcrystalline                                                              cellulose)                                                                     Polyplasdone XL    97 10.37  9.333                                             (Crospovidone)                                                                 Cab-O-Sil    5  0.54  0.486                                                    (Colloidal Silicon                                                             Dioxide)                                                                       TOTAL   935 100 90                                                           ______________________________________                                    

EXAMPLE 3 High Potency E Formula III Containing Acacia

    ______________________________________                                         Ingredients       75% E   80% E                                                ______________________________________                                         1. Vitamin E Acetate                                                                             75.0*   80.0*                                                  2. HPMC E15LV 15.0 12.0                                                        3. Acacia 10.0 8.0                                                             Total 100.0% 100.0%                                                          ______________________________________                                          *Additional 2% overage was added.                                        

Procedure

1. Gum acacia solution (20% by weight) was prepared in a 4 l beaker as follows:

    ______________________________________                                         Preparation of 20% gum acacia                                                    Time (min.)                                                                              Temp. (° C.)                                                                      Stirrer                                                                               Amount                                                                               Comments                                    ______________________________________                                          0      21° C.                                                                            on       2 l   Add water into beaker                           151 39° C. on, slow 0.5 kg Add gum acacia                               175 36° C. on, fast  Addition completed                                 190 37° C. on, fast  Begin heating                                      208 63° C. on, slow                                                     279 71° C. --  Add to emulsion                                        ______________________________________                                    

2. 10% Methocel E 15LV solution was prepared as in Example 1.

3. Vitamin E acetate was added to Methocel solution according to the above formulas and homogenized to produce an emulsion as in Example 1.

4. The resulting emulsion was heated to 80-90° C. with slow (200 r.p.m.) agitation.

5. An appropriate amount of 20% acacia solution from step 1 was added.

6. The mixture from above was blended with gentle agitation for an additional 15 minutes while the temperature were maintained at 70-90° C.

7. Spray the vitamin E suspensions at the following conditions.

    __________________________________________________________________________     Spray drying of the vitamin E suspension                                         The suspension was pumped from the FRYMA processing unit to the spray        tower by a gear                                                                  pump and then atomized by a rotary atomizer manufactured by Niro, Inc.                            Set                                                                                          Set Inlet Inlet Set outlet Outlet                                            Pressure Pressure In at air                     Time Temp. Temp. Temp. Temp. Tower Tower flow in                               (min.) (° C.) (° C.) (° C.) (° C.). in mbar                                       in mbar m3/n Comments                         __________________________________________________________________________      0  180     100      -5          Start up lower*                                 50 180 181 100 101 -5 -3 1500 Start spray                                              drying                                                                 60 180 181 100 100 -5 -3 1500                                                  62        Spray drying                                                                 ended                                                                __________________________________________________________________________      *Shorthand for start up the spray dryer from a lower inlet temperature. I      is standard procedure to start up a spray dryer at low temperature, then       gradually increase the inlet temperature to reach a proper outlet              temperature, and to establish an equilibrium condition.                  

EXAMPLE 4 30% Vitamin A Products Using Hydroxypropyl Methylcellulose as the Primary Polymer, and Sodium Alginate, HPMCP HP-55, or Acacia as the Secondary Polymer

    ______________________________________                                         Ingredient     Formula I Formula II                                                                               Formula III                                 ______________________________________                                         Vitamin A Palmitate                                                                           30.0 ± 2.5*                                                                           30.0 ± 2.5*                                                                           30.0 ± 2.5*                                Butylated Hydroxyanisole 1.0 1.0 1.0                                           (BHA)                                                                          Butylated Hydroxytoluene 3.0 3.0 3.0                                           (BHT)                                                                          Methocel E15LV 50.8 42.4 50.8                                                  HPMCP, HP-55S -- 21.1 --                                                       Acacia -- -- 12.7                                                              Sodium Alginate 3.4 -- --                                                      Calcium Chloride 1.7 -- --                                                     PHARMACOAT 606 7.6 -- --                                                     ______________________________________                                          Note: * % Overage                                                        

Procedure

Formulation I

Composition

    ______________________________________                                         Material           content (%)                                                                              weight (kg)                                       ______________________________________                                         Vitamin A palmitate 1.7 MIU/g                                                                     32.47     1.30                                                BHA 1 0.04                                                                     BHT 3 0.12                                                                     METHOCEL E15LV premium 50.82 2.03                                              Sodium alginate 3.39 0.136                                                     Calcium chloride 1.69 0.068                                                    PHARMACOAT 606 7.62 0.305                                                    ______________________________________                                    

General

All the solutions were prepared using degassed deionized water under nitrogen. Vitamin A palmitate was shielded from light.

Preparation of a 12% Solution of METHOCEL E15LV

Water (8 l) was heated to 85° C. METHOCEL E15LV powder (2.03 kg) was slowly added into the water while mixing with rapid agitation until a uniform suspension was obtained and thoroughly dispersed. Additional cold water (6.89 l) was quickly added to the suspension and the temperature was cooled to 25° C.

Preparation of a 5% Solution of Sodium Alginate

Sodium alginate powder (0.136 kg) was added into 2.58 liters of cold water with proper agitation and heated to 80-90° C. The solution was kept at 70° C. until used.

Preparation of a 5% Solution of Calcium Chloride

Calcium chloride (0.068 kg) was dissolved in 1.29 l of water. The solution was kept at room temperature until used.

Preparation of a 12% Solution of PHARMACOAT 606

Water (0.75 l) was heated to 90° C. PHARMACOAT 606 powder (0.305 kg) was slowly added into the water while mixing with proper agitation until a uniform suspension was formed. Cold water (1.50 l) was added quickly to the suspension and the temperature was cooled to 25° C. The solution was maintained at room temperature with gentle agitation until used.

Preparation of the Emulsion/suspension

BHA (0.04 kg) and 0.12 kg BHT were added to 1.3 kg vitamin A palmitate and mixed until a clear solution was formed. The resulting solution was added to the METHOCEL E15LV solution and emulsified for 30 minutes with the colloidal mill. (The oil droplet size measured using a MALVERN Autosizer was 757 nm). The emulsion was then heated to 75° C. while slowly mixing (200 r.p.m.) with an anchor stir bar to form a suspension. The 70° C. sodium alginate solution was added to the suspension and stirred for 15 minutes. Calcium chloride solution was added, and the mixture was cooled. PHARMACOAT solution was added at room temperature and mixed for 10 minutes. The mixture was then heated to 65° C. while mixing slowly with an anchor stir bar. (the suspension had a viscosity of 11,400 cps/65° C.). The suspension was then diluted with 2 l hot water to adjust the viscosity to 2,500 cps/65° C.

Spray Drying

See below (spray dry results are shown in FIGS. 6-9).

Formulation II

Composition

    ______________________________________                                         Material           content (%)                                                                              weight (kg)                                       ______________________________________                                         Vitamin A palmitate 1.7 MIU/g                                                                     32.47     1.46                                                BHA 1 0.045                                                                    BHT 3 0.135                                                                    METHOCEL E15LV premium 42.44 1.91                                              HPMCP 55 21.09 0.95                                                          ______________________________________                                    

General

All the solutions were prepared using degassed deionized water under nitrogen. Vitamin A palmitate was shielded from light.

Preparation of a 12% Solution of METHOCEL E15LV

Water (8 l) was heated to 85° C. METHOCEL E15LV powder (2.03 kg) was slowly added into the water while mixing with rapid agitation until a uniform suspension was obtained and thoroughly dispersed. Additional cold water (6.89 l) was quickly added to the suspension and the temperature was cooled to 25° C.

Preparation of a 15% Solution of HPMCP

HPMCP powder (0.95 kg) was added to 4.28 l of 0.5 N NaOH with proper agitation and heated to 70° C. Hot (70° C.) water (1.1 l) was added after the powder completely dissolved. The solution was kept at 70° C. until used.

Preparation of the Emulsion/suspension

BHA (0.045 kg) and 0.135 kg BHT were added to 1.46 kg vitamin A palmitate and mixed until a clear solution was formed. The solution was added to the METHOCEL E solution and emulsified for 30 minutes using a colloidal mill. The oil droplet size measured using a particle size analyzer (MALVERN Autosizer 2C manufactured by Malverne Instruments, Inc.) was 888 nm. Then, the emulsion was heated to 75° C. while slowly stirring (200 r.p.m.) with an anchor stir bar to form a suspension. The 70° C. HPMCP solution was added to the suspension and continuously stirred with an anchor agitator. The pH was adjusted to 6.9 with 0.5 of 1 N NaOH (pH before: 5.28). The resulting suspension had a viscosity of 500 cps/70° C.

Spray Drying

See below.

Formulation III

Composition

    ______________________________________                                         Material           content (%)                                                                              weight (kg)                                       ______________________________________                                         Vitamin A palmitate 1.7 MIU/g                                                                     32.47     1.46                                                BHA 1 0.045                                                                    BHT 3 0.135                                                                    METHOCEL E15LV premium 50.82 2.29                                              Gum acacia 12.7 0.58                                                         ______________________________________                                    

General

All solutions were prepared using degassed deionized water under nitrogen. Vitamin A palmitate was shielded from light.

Preparation of a 10% Solution of METHOCEL E

Water (6.2 l) was heated to 85° C. METHOCEL E15LV powder (2.29 kg) was slowly added into the water while mixing with rapid agitation until a uniform suspension was obtained. Additional cold water (14.41 l) was quickly added to the suspension and the temperature was cooled to 25° C.

Preparation of a 20% Solution of Gum Acacia

Gum acacia powder (0.58 kg) was dissolved to 2.32 l cold water and heated to 70° C. The solution was kept at 70° C. until used.

Preparation of the Emulsion/suspension

BHA (0.045 kg) and 0.135 BHT were added to 1.46 kg vitamin A palmitate and mixed until a clear solution was formed. The solution was added to the METHOCEL E solution and emulsified for 30 minutes with the colloidal mill. The oil droplet size measured using MALVERN Autosizer 2C was 854 nm. The emulsion was then heated to 75° C. while mixing with an anchor bar to form a suspension. The 70° C. gum acacia solution was added to the suspension and stirred with an anchor agitator. The pH was adjusted to 7.2 with 40 ml of 0.5 N NaOH (pH before: 6.37). The resulting suspension had a measured viscosity of 1060 cps/70° C.

Spray Drying

See below.

Spray Drying Conditions for Formulations I, II and III

    ______________________________________                                                                    Inlet Outlet                                                                               Inlet                                     Formu- Feed Vis-  Air Air Air Wheel                                            lation Temp; cosity  Temp. Temp. Flow Speed                                    Number (° C.) (cps) pH (° C.) (° C.) m.sup.3 /h                                                      (rpm)                             ______________________________________                                         I      65      2,500/  --  165   100   1,500 8,500                                 65° C.                                                                II 70 500/ 6.9 165 100 1,500 8,500                                               70° C.                                                                III 70 1,060/ 7.2 160 100 1,500 8,500                                            70° C.                                                              ______________________________________                                    

2% silicic acid (type FK 320 DS) was added in each trial. Pressure inside the tower was always about -4 mbar.

The subject invention has been described in terms of its preferred embodiments. However, one skilled in the art will recognize various alternative embodiments having read the specification. These variations are to be considered within the scope and spirit of the invention which is only to be limited by the claims which follow and their equivalents. 

What is claimed is:
 1. A method for producing a composition, which comprises:(a) incorporating an oleophilic substance into a primary polymer-containing solution; (b) solidifying the primary polymer under mixing conditions to encapsulate the oleophilic substance within the polymer and form a primary particle; and (c) adding a secondary polymer under mixing conditions to further encapsulate at least one primary particle within the secondary polymer and form the composition.
 2. The method of claim 1 further comprising selecting a primary polymer from the group consisting of cellulose.
 3. The method of claim 2, wherein the cellulose is selected from the group consisting of methylcellulose and hydroxypropyl methylcellulose.
 4. The method of claim 1 further comprising selecting a secondary polymer from the group consisting of cellulose, cellulose derivatives, alginate, acacia, gelatin, maltodextrin, calcium lactate, and modified starches.
 5. The method of claim 4, wherein the secondary polymer is a cellulose selected from the group consisting of methylcellulose and hydroxypropyl methylcellulose.
 6. The method of claim 4, wherein the secondary polymer is a cellulose derivative selected from the group consisting of hydroxypropylmethyl cellulose phthalate.
 7. The method of claim 4, wherein the secondary polymer is a gelatin which is a fish gelatin.
 8. The method of claim 4, wherein the secondary polymer is maltodextrin.
 9. The method of claim 8, wherein the maltodextrin has a dextrose equivalent value of about
 18. 10. The method of claim 4, wherein the secondary polymer is a modified starch selected from the group consisting of pregelatinized corn starch and hydroxypropyl starch.
 11. The method of claim 4, wherein the secondary polymer is calcium lactate.
 12. The method of claim 1, wherein the secondary polymer is cross-linked after it is added to the primary particle.
 13. The method of claim 12, wherein the cross-linking is effected by changing the pH, or by adding a cross-linking agent.
 14. The method of claim 13, wherein the cross-linking agent is selected from the group consisting of sugar, acacia, cations, and gelatin.
 15. The method of claim 1, wherein the second polymer is coated onto the primary particle.
 16. The method of claim 15, wherein coating comprises spray drying or beadletting.
 17. The method of claim 1, wherein the mixing conditions comprise stirring with an anchor stirrer at about 200 r.p.m.
 18. The method of claim 1, wherein the secondary polymer encapsulates at least two primary particles. 